I Need help clearing the last Combo Mission Battle! Help?

What makes this immensely difficult, is that I'm going up against a Metal Grappler, which as many know by now, has a reduced Down Time.This battle is driving me absolutely freaking NUTS!I don't lose in Health, but I can't seem to get a high-enough Combo to claim a legitimate win.

I don't remember how I managed it the first time....[ I reset my game for a fresh start, just for kicks.]

Yeah what czqx said. It's just jumping then immediately after jump you fire your gun. Do that a lot with the gravity gun until the dumb cpu jumps into your shots. throw in your pods and bombs too to add damage.